On August 6 and 9, 1945, the cities of Hiroshima and Nagasaki
were destroyed by the first atomic bombs used in warfare.

Documents on the decision to use the atomic bomb are reproduced
here in full-text form, and many
also as images. All transcriptions are by Gene Dannen.
In most cases, the original documents are in the U.S.
National Archives. Other aspects of the decision are shown from
accounts by the participants. This page was new May 29, 1995, and it was
last updated January 25, 2018.

International Law - Bombing of Civilians
- At the beginning of World War II, the bombing of
civilians was regarded as a barbaric act. As the war continued,
however, all sides abandoned previous restraints. But international law has
always distinguished between civilians and combatants. Legal
context to the decision, from a variety of international
treaties and the 1996 World Court opinion.
Target Committee, Los Alamos, May 10-11, 1945 - Minutes of the
Target Committee, meeting in the office of J. Robert Oppenheimer,
as they decided the best use of the “gadget.”
The Franck Report, June 11, 1945 - The Franck Report, written by
a seven-man panel of scientists at the University of Chicago, urged
that the bomb be demonstrated “before the eyes of representatives of
all United Nations, on the desert or a barren island.”
Scientific Panel, June 16, 1945 - Despite the arguments against
using the bomb made by the Franck Report, a panel composed of
Oppenheimer, Fermi, Compton, and Lawrence found “no acceptable
alternative to direct military use.”
Bard Memorandum, June 27, 1945 - Undersecretary of the Navy
Ralph A. Bard wrote that use of the bomb without warning was
contrary to “the position of the United States as a great
humanitarian nation,” especially since Japan seemed close to
surrender.
Setting the Test Date, July 2, 1945
- President Truman had delayed his meeting with Stalin until the
atomic bomb could be tested. On July 2, General Groves told Robert
Oppenheimer that the test date was being set by “the upper
crust.”
Szilard Petition, first version, July 3, 1945
- The first version of Leo Szilard’s petition called atomic bombs
“a means for the ruthless annihilation of cities.” It asked the
President “to rule that the United States shall not, in the
present phase of the war, resort to the use of atomic bombs.”
Petition cover letter, July 4, 1945 - Szilard sent copies of the
July 3 version of his petition to colleagues at Oak Ridge and Los
Alamos. This cover letter discussed the need for scientists to take
a moral stand on the use of the bomb.
Groves Seeks Evidence, July 4, 1945 - As Szilard circulated his
petition, General Groves sought ways to take action against him. On
July 4, 1945, Groves wrote to Lord Cherwell, Winston Churchill’s
science advisor.
Oak Ridge petition, July 13, 1945 - The first version of
Szilard’s petition inspired a similar petition at the Manhattan
Project laboratory at Oak Ridge, Tennessee. The names of the 18
signers are included.
Oak Ridge petition, mid-July 1945 - Another petition at Oak
Ridge called for the power of the bomb to be “adequately described
and demonstrated” before use. The names of the 67 signers are
included.
Trinity Test, July 16, 1945 - Radiation Monitoring - The test of
the atomic bomb in the New Mexico desert on July 16 was a
spectacular success. This report by Manhattan Project Chief of
Medical Section Stafford Warren shows that radioactive fallout from
the test was an important concern.
Trinity Test, July 16, 1945 - Eyewitness Accounts
- Even 32 kilometers (20 miles) away, scientists felt the heat of
the explosion on exposed skin. Declassified eyewitness accounts of
the Trinity test by Luis Alvarez, Enrico Fermi, Philip Morrison,
Robert Serber, Victor Weisskopf, and others.
Szilard Petition, July 17, 1945 - Leo Szilard, and 69 co-signers
at the Manhattan Project “Metallurgical Laboratory” in Chicago,
petitioned the President of the United States. The names and
positions of the signers are included.
Szilard Petition, July 17, 1945 - Full-color Image
- See Szilard’s petition. Though it contained no secret information,
the petition was not declassified until 1957.
Truman Tells Stalin, July 24, 1945
- At the Potsdam Conference in defeated Germany, President Truman
told Stalin only that the U.S. “had a new weapon of unusual
destructive force.” What did Truman say, and what did Stalin
understand? Seven eyewitness accounts.
Truman Diary, July 25, 1945
- President Truman told his diary that he had ordered the bomb dropped
on a “purely military” target, so that “military objectives and
soldiers and sailors are the target and not women and children.”
Official Bombing Order, July 25, 1945
- The bombing order issued to General Spaatz made no mention of
targeting military objectives or sparing civilians. The cities
themselves were the targets.
Bomb Production Schedule, July 30, 1945 - The Manhattan
Project was designed to make far more than a few bombs.
The production rate of 3 bombs per month in August was expected to rise to
5 bombs/month in November, and 7 bombs/month in December.
Groves-Oppenheimer transcript, August 6, 1945 - General Groves
informed Robert Oppenheimer of the Hiroshima bombing. Transcript
of telephone conversation.
Truman radio speech, August 9, 1945 (excerpt) - In his radio speech to the
nation on August 9, President Truman called Hiroshima “a
military base.” This is an audio file. Hear Truman say it.
Or read the full text of that paragraph.
Truman Revokes Bombing Order, August 10, 1945
- Horrified by reports of the
enormous casualties in Hiroshima and Nagasaki, Truman ordered the atomic
bombing stopped.
Leo Szilard, Interview: “President Truman Did Not Understand”
- A 1960 interview with Leo Szilard about the use of the bomb, reprinted
by permission from U.S. News & World Report.

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